Exhaust aftertreatment systems are used to receive and treat exhaust gas generated by IC engines. Conventional exhaust gas aftertreatment systems include any of several different components to reduce the levels of harmful exhaust emissions present in exhaust gas. For example, certain exhaust aftertreatment systems for diesel-powered IC engines include a selective catalytic reduction (SCR) catalyst to convert NOx (NO and NO2 in some fraction) into harmless nitrogen gas (N2) and water vapor (H2O) in the presence of ammonia (NH3). Generally in such conventional aftertreatment systems, an exhaust reductant, (e.g., a diesel exhaust fluid such as urea) is injected into the aftertreatment system to provide a source of ammonia, and mixed with the exhaust gas to partially reduce the NOx gases. The reduction byproducts of the exhaust gas are then fluidically communicated to the catalyst included in the SCR aftertreatment system to decompose substantially all of the NOx gases into relatively harmless byproducts which are expelled out of such conventional SCR aftertreatment systems.
An exhaust reductant is generally inserted into the SCR system as the source of ammonia to facilitate the reduction of constituents such as NOx gases of the exhaust gas (e.g., a diesel exhaust gas). The exhaust reductant is stored in a reductant storage tank and communicated to the SCR system. The reductant generally includes an aqueous solution such as an aqueous urea solution. Reductant insertion assemblies are generally used to deliver the reductant from the reductant storage tank.
The urea or any other source of ammonia inserted into aftertreatment system can be deposited on sidewalls and/or components of the aftertreatment system. The amount and rate of reductant deposits in the aftertreatment system can be a function of the pressure at which the reductant is inserted into the aftertreatment system and/or any other parameters which can affect efficient mixing of the reductant with the exhaust gas. Increases in reductant deposits can lead to inefficient mixing of the exhaust gas with the reductant, variations in temperature of the exhaust gas and/or increase in backpressure experienced by the exhaust gas flowing through the aftertreatment system, all of which can negatively impact a catalytic conversion efficiency of the aftertreatment system.